Hey guys,
This is my first post on this forum. I made an account just to ask this question that has been driving me insane for months. I bought a MiniDisplay Port to HDMI cable a few months ago to display a second screen on my Toshiba Regza HDTV. I plugged the cables in and clicked Detect Displays in System Preferences. Nothing happened...

Today, I bought a new, different brand MiniDisplay Port to HDMI cable hoping that maybe the last adapter I bought was faulty. I plugged everything in again, clicked Detect Displays and...nothing.

Does this mean it is an issue with my HDTV? I cannot find my HDTV manual, but this is a fairly new TV (3 to 4 years old) with 4 HDMI ports and 1080p, so I assume it supports this sort of functionality. My iMac is an 8.1. This is the model of my HDTV. (I did not buy it from this site.)

Any sort of feedback or tips would be appreciated. Thank you!